An armrail structure is important to a collapsible playpen for protecting the infant from falling out of the playpen and for convenience in use. A conventional armrail release device for folding and expanding the armrails of a collapsible playpen is complex in structure and does not permit easy operations of folding and expanding the playpen. In addition, the conventional armrail release device is usually hidden in a fabric enclosure such that a user cannot recognize the actual position of the armrail release device easily, thereby greatly causing an inconvenience in use.
The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional armrail release device for a playpen.